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If a family has three children, what is the probability that

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If a family has three children, what is the probability that [#permalink] New post 23 Jan 2018, 15:16
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If a family has three children, what is the probability that the family has at least one girl?

1

0.875

0.75

0.50

0.375

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[Reveal] Spoiler: OA

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Re: If a family has three children, what is the probability that [#permalink] New post 24 Jan 2018, 02:58
Total ways: 8
1-(Not a single girl)
1-1/8
7/8
0.87
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Re: If a family has three children, what is the probability that [#permalink] New post 25 Jan 2018, 04:30
First, calculate ALL the possible constellations:
2*2*2 = 8 possible combinations.
Of the 8, only 1 combination includes NO girl (the question can also be thought of asking what the probability would be for the family to have NO girls at all and then subtract this probability from 1).
So the probability of at least 1 girl is 7/8 or 0.875 -> answer B
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Re: If a family has three children, what is the probability that [#permalink] New post 03 Feb 2018, 04:08
Great Job!!!
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Re: If a family has three children, what is the probability that [#permalink] New post 04 Feb 2018, 11:25
Im not sure about the answer I thought it was 75. Im not good at probability so I might be wrong:

BBB
GGG
GBB
GGB

these are four possible choices. At least one girl means having 1 2 or 3 girls so 3/4=.75

if you do

2*2*2 you will double count the same arrangements right?

_ _ _
B B G
G B B
B G B
...
etc

like flipping a coin and getting: T T H = H T T.
Re: If a family has three children, what is the probability that   [#permalink] 04 Feb 2018, 11:25
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